This invention relates to a method and apparatus for unloading green tires from, and positioning new carcasses on, a green tire assembly drum, and more particularly to a carcass loading apparatus which is incorporated into an unloader for assembled green tires.
The basic elements of modern radial-ply pneumatic tires include an inner liner, one or more radial plies, side walls, beads and fillers, etc., all combined to form a carcass, and one or more belts made of steel cord or other cord materials combined with tread stock material to form a belt-tread stock assembly. These two assemblies are then combined to form a green tire, which is subsequently vulcanized in a mold to form a completed radial tire.
The first stage assembly, referred to herein as the "green tire carcass" consists of an inner liner plus one or more body plies of rubber-coated cord material, a pair of axially spaced parallel bead assemblies, layers of the ply material which encompass the bead assemblies, and side wall stock material, all of which when combined, comprise a first stage assembly. These tire elements are assembled and consolidated on a cylindrical carcass building drum such that the one or more body plies (in the case of a radial tire) have the body ply cords essentially parallel to the rotational axis of the building drum as the carcass is assembled thereon, for example, extending along the cylindrical carcass.
The two beads are anchored to the opposing axial extremities of the first stage carcass, for example, by folding part of the plies inward around the respective beads, the beads being parallel one to the other and co-axial with the rotational axis of the carcass, and the two layers of side wall stock are circumferentially consolidated to the outer surface of the carcass, axially disposed one from the other and each adjacent to one of the beads. The completed carcass is later transformed from the cylindrical shape to that of a toroid so the radial body cords, being essentially parallel to the rotational axis, are made to assume the configuration of meridians to the rotational axis of the carcass.
The second assembly is prepared by consolidating one or more relatively non-extensible belts, of suitable cord, (for example, steel wire in the case of a steel-belted tire) incorporated into uncured rubber stock, with a band of tread stock. Then the belt-tread stock assembly is consolidated with a toroidal shaped carcass, producing a finished green radial tire which is removed from the building machine and placed in a suitable mold for final shaping and vulcanization of the various rubber components, thereby forming a completed cured tire.
U.S. Pat. No. 4,445,963 shows a conventional apparatus for building a green tire, where the assembly includes a support track having a green tire building section mounted at one end and a belt and tread stock building section at an opposite end of the track. The green tire building section includes a green tire assembly drum mounted to a cantilevered shaft which extends from a suitable head stock. The belt and tread stock building section includes a rotatably mounted drum which is extensible and contractible for building different sizes of second assemblies. A transfer mechanism is also typically included intermediate the green tire building section and the belt and tread stock building section, the transfer mechanism being movable to place a completed belt-tread stock assembly over a completed carcass, which is located on the green tire building drum.
In a typical green tire assembly process, the operator must first remove a completed green tire from the green tire building drum and carry it to a storage rack or place it onto a take-away conveyor. He must then step over to a carcass storage rack and pick up a carcass that was completed elsewhere, carry it to the green tire building drum, lift it and place it thereupon. Thus, carcass loading is an interdependent function which must follow green tire unloading immediately to assure maximum utilization of the costly tire assembly equipment. The green tire building drum will then transform the cylindrically shaped carcass into a toroid which is then ready to receive the belt/tread assembly which was built on the belt tread stock building drum and which is being delivered to the toroidal-shaped carcass by the transfer mechanism. A suitable stitcher mechanism is then engaged to consolidate the two component assemblies into a completed green tire which is then released by the drum so that it can be removed.